JP2010207700A - Methane fermentation apparatus and methane fermentation method - Google Patents

Abstract

The present invention provides a low-cost methane fermentation treatment apparatus capable of suppressing the precipitation of MAP in a membrane permeate outlet piping while maintaining the inside of a methane fermentation tank at a pH suitable for methane fermentation.
SOLUTION: An organic substance solubilized in liquid form at a temperature higher than that of digested sludge in a methane fermentation tank 12 is supplied to the methane fermentation tank 12, and the digested sludge in the methane fermentation tank 12 is concentrated by a membrane separation means 13. The methane fermentation treatment apparatus 11 performs methane fermentation treatment while the inside of the membrane permeate discharge pipe 30 and the membrane permeate discharge pipe 30 for taking out the membrane permeate that has passed through the separation membrane 19 of the membrane separation means 13 and the inside of the membrane permeate discharge pipe 30 are shown. Heat exchange means for heating the membrane permeate by heat exchange between the flowing membrane permeate and the organic substance in the solubilization tank 15 is provided. A partially formed coiled tube portion 30 a is provided in the solubilization tank 15.
[Selection] Figure 1

Description

  The present invention relates to a methane fermentation treatment apparatus and a methane fermentation treatment method for treating methane fermentation of high-temperature organic substances containing a large amount of phosphorus, magnesium, nitrogen, etc., such as distilled liquor from alcohol and alcohol production processes, food factory waste, etc. About.

  Conventionally, as this type of methane fermentation treatment apparatus, as shown in FIG. 5, the digested sludge in the methane fermentation tank 51 is concentrated by the submerged membrane separation means 52 while circulating between the membrane separation tank 53. Some perform methane fermentation. The membrane separation means 52 is installed in the membrane separation tank 53, and the membrane separation tank 53 communicates with the methane fermentation tank 51. A solubilization tank 54 is installed in the preceding stage of the methane fermentation tank 51. Further, a biological treatment tank 55 for biologically treating the membrane permeate that has permeated through the separation membrane of the membrane separation means 52 is installed at the subsequent stage of the methane fermentation tank 51.

Between the membrane separation tank 53 and the biological treatment tank 55, a membrane permeate outlet piping 56 for transferring the membrane permeate from the membrane separation means 52 to the biological treatment tank 55 is provided.
According to this, the organic substance solubilized in a liquid state in the solubilization tank 54 is put into the methane fermentation tank 51, and usually subjected to methane fermentation at a temperature of about 35 to 60 ° C. Digested sludge in the methane fermentation tank 51 is concentrated by solid-liquid separation by the membrane separation means 52. At this time, the membrane permeate that has passed through the separation membrane of the membrane separation means 52 is sucked by the suction pump 57, flows through the membrane permeate outlet piping 56, is sent to the biological treatment tank 55, and is biologically treated in the biological treatment tank 55. After that, it is discharged as a treatment liquid into a river or the like.

  In addition, examples of the organic substance include a distillation waste liquid generated when making distilled spirits such as shochu and whiskey. Such a distillation waste liquid usually has a temperature of about 70 to 80 ° C., and contains phosphorus, magnesium. The content of the inorganic components such as nitrogen and nitrogen is high, and magnesium ammonium phosphate (hereinafter abbreviated as MAP) is easily generated during the methane fermentation treatment step. In particular, in the membrane permeate outlet piping 56, the membrane permeate is cooled by outside air, so that an environment in which inorganic crystals of MAP are easily generated on the inner peripheral surface of the membrane permeate outlet piping 56 is formed, and this inorganic crystal grows gradually. Therefore, there is a problem that the membrane permeate outlet piping 56 is blocked.

As a countermeasure for such a problem, a large amount of a chemical such as iron salt is added to the methane fermenter 51 in order to suppress the formation of inorganic crystals of MAP.
Patent Document 1 below describes that a part of the digested sludge in the methane fermentation tank is drawn out, concentrated with a concentrator, and the concentrated separation liquid of the concentrator is discharged into sewers as treated water. Furthermore, when MAP crystals are precipitated in the concentrated separation liquid transfer pipe, tap water, industrial water, secondary treated water, etc. are introduced into the concentrated separation liquid to lower the concentration and suppress MAP precipitation. Is described.

JP-A-2005-199258

  However, in the conventional format shown in FIG. 5 above, there is a problem that the cost required for the addition of the chemical is high, or the pH in the methane fermentation tank 51 fluctuates due to the addition of the chemical, and the inside of the methane fermentation tank 51 is optimal for methane fermentation. There is a problem that it is difficult to maintain a stable pH.

  Moreover, in what was shown in the said patent document 1, by introduce | transducing tap water, industrial water, a sewage secondary-treatment water, etc. into a concentrated separation liquid, the concentrated separation liquid is diluted and ammonia, phosphorus, etc. which are contained in a concentrated separation liquid Therefore, there is a problem that the amount of the concentrated separation liquid greatly fluctuates.

  The present invention provides a low-cost methane fermentation treatment apparatus and a methane fermentation treatment method capable of suppressing the precipitation of MAP in the membrane permeate outlet piping while maintaining the inside of the methane fermentation tank at a pH suitable for methane fermentation. The purpose is to provide.

In order to achieve the above object, the first invention is a methane fermentation tank for performing a methane fermentation treatment of an organic substance in digested sludge, and an organic solvent having fluidity and higher temperature than the digested sludge in the methane fermentation tank. A raw material supply means for supplying a sexual substance to a methane fermentation tank, and a membrane separation means,
A methane fermentation treatment apparatus for performing a methane fermentation treatment while concentrating solids in digested sludge in a methane fermentation tank by a membrane separation means,
A membrane permeate outlet pipe for taking out the membrane permeate permeated through the separation membrane of the membrane separator means, a membrane permeate flowing in the membrane permeate outlet pipe and an organic substance supplied to the methane fermentation tank by the raw material supply means; Heat exchange means for warming the membrane permeate by performing heat exchange between the two.

  According to this, the organic substance solubilized at high temperature and in a liquid state is supplied to the methane fermentation tank by the raw material supply means, and is subjected to methane fermentation treatment in the methane fermentation tank. The digested sludge in the methane fermentation tank is concentrated by membrane separation means. At this time, the membrane permeate that has passed through the separation membrane of the membrane separation means flows through the membrane permeate outlet pipe and is taken out to the outside.

  At this time, the heat exchange means performs heat exchange between the membrane permeate flowing in the membrane permeate outlet piping and the high-temperature organic substance supplied to the methane fermentation tank to heat the membrane permeate, Since the decrease in the solubility product of MAP accompanying the decrease in the temperature of the membrane permeate in the membrane permeate outlet pipe is suppressed, it becomes an environment in which inorganic crystals of MAP hardly precipitate, and MAP is formed on the inner peripheral surface of the membrane permeate outlet pipe. Precipitation can be suppressed.

  As a result, the amount of chemicals such as iron salt (the amount used) can be significantly reduced, which can reduce the cost, and the pH within the methane fermentation tank can be easily optimized for methane fermentation. Can be maintained.

Moreover, since the membrane permeate is heated using the temperature of the high-temperature organic substance supplied to the methane fermentation tank, the temperature of the organic substance can be used effectively, and the cost can be further reduced.
In the second invention, the raw material supply means has a solubilization tank for solubilizing the organic substance in a liquid or slurry state,
The heat exchange means has a configuration in which the membrane permeate outlet piping passes through the solubilization tank.

  According to this, when the membrane permeate flows through the membrane permeate outlet piping and is taken out to the outside, it is between the membrane permeate in the membrane permeate outlet and the high temperature organic substance stored in the solubilization tank. Then, heat exchange is performed and the membrane permeate is heated. Thereby, the temperature fall of the membrane permeate in the membrane permeate outlet pipe is suppressed.

In the third aspect of the present invention, the raw material supply means has a storage tank for storing an organic substance having fluidity,
The heat exchange means has a configuration in which the membrane permeate outlet piping passes through the storage tank.
According to this, when the membrane permeate flows through the membrane permeate outlet piping and is taken out to the outside, between the membrane permeate in the membrane permeate outlet and the high temperature organic substance stored in the storage tank. Heat exchange is performed to warm the membrane permeate.

In the fourth invention, the raw material supply means has a raw material supply pipe for supplying a fluid organic substance to the methane fermentation tank,
The heat exchange means has a configuration in which the membrane permeate outlet piping and the raw material supply piping abut.

  According to this, when the membrane permeate flows through the membrane permeate outlet pipe and is taken out to the outside, heat exchange is performed between the membrane permeate in the membrane permeate outlet pipe and the high-temperature organic substance in the raw material supply pipe. Is performed to warm the membrane permeate. Thereby, the temperature fall of the membrane permeate in the membrane permeate outlet pipe is suppressed.

In the fifth aspect of the invention, the heat exchange means exchanges heat between the membrane permeate and the organic material supplied to the methane fermentation tank by the raw material supply means via a heat medium.
According to this, when the membrane permeate flows through the membrane permeate outlet piping and is taken out to the outside, between the membrane permeate in the membrane permeate outlet and the high temperature organic substance supplied to the methane fermentation tank Then, heat exchange is performed via the heat medium, and the membrane permeate is heated. Thereby, the temperature fall of the membrane permeate in the membrane permeate outlet pipe is suppressed.

In the sixth aspect of the present invention, an organic substance that is solubilized in liquid form at a higher temperature than the digested sludge in the methane fermenter is supplied to the methane fermenter, and the digested sludge in the methane fermenter is concentrated by membrane separation means. A methane fermentation treatment method for performing methane fermentation treatment while
The membrane permeate is heated by exchanging heat between the membrane permeate passing through the separation membrane of the membrane separation means and flowing in the membrane permeate outlet piping and the organic substance supplied to the methane fermentation tank. is there.

  As described above, according to the present invention, it is possible to suppress the precipitation of MAP in the membrane permeate outlet piping at low cost while maintaining the inside of the methane fermentation tank at a pH suitable for methane fermentation.

It is a figure of the methane fermentation processing apparatus in the 1st Embodiment of this invention. It is a figure of the methane fermentation processing apparatus in the 2nd Embodiment of this invention. It is a figure of the methane fermentation processing apparatus in the 3rd Embodiment of this invention. It is a figure of the methane fermentation processing apparatus in the 4th Embodiment of this invention. It is a figure of the conventional methane fermentation processing apparatus.

Hereinafter, a first embodiment of the present invention will be described with reference to FIG.
11 is a methane fermentation treatment apparatus that performs methane fermentation treatment while concentrating the digested sludge in the methane fermentation tank 12 by solid-liquid separation by the submerged membrane separation means 13. The methane fermentation treatment apparatus 11 has raw material supply means 14 for supplying an organic substance having a higher temperature and fluidity than the digested sludge in the methane fermentation tank 12 to the methane fermentation tank 12.

  The raw material supply means 14 is installed in the front | former stage of the methane fermentation tank 12, and is connected to the solubilization tank 15 which solubilizes the said high temperature organic substance in a liquid form or a slurry form, and the methane fermentation tank 12 and the solubilization tank 15. A raw material supply pipe 16 and a supply pump 17 provided in the raw material supply pipe 16 are provided.

  Further, a biological treatment tank 20 for biologically treating the membrane permeate that has permeated through the separation membrane 19 of the membrane separation means 13 is installed at the subsequent stage of the methane fermentation tank 12. The biological treatment tank 20 has a denitrification tank 21 and a nitrification tank 22. The nitrification tank 22 is provided with aeration means 23.

  The membrane separation means 13 is provided in a membrane separation tank 25 communicating with the methane fermentation tank 12, and a plurality of flat plate membrane cartridges arranged in parallel with a predetermined interval are arranged in the vertical direction. A flow path is formed between the membrane cartridges. Each membrane cartridge has a separation membrane 19 (filtration membrane) disposed on both sides of the filter plate.

  Further, in the membrane separation tank 25, an aeration means 26 for diffusing the biogas in the methane fermentation tank 12 from below the membrane separation means 13 is provided. A blower device 28 is provided in the gas supply passage 27 for supplying the biogas in the methane fermentation tank 12 to the aeration means 26.

  Between the membrane separation means 13 and the biological treatment tank 20, there is a membrane permeate outlet pipe 30 for taking out the membrane permeate that has permeated the separation membrane 19 of the membrane separation means 13 from the membrane separation means 13 to the external denitrification tank 21. Is provided. One end of the membrane permeate outlet pipe 30 communicates with a permeate channel formed in the membrane cartridge, and the other end communicates with the denitrification tank 21.

  The membrane permeate outlet pipe 30 communicates with the coiled first tube portion 30a provided at the bottom of the solubilization tank 15, the permeate flow path of the membrane cartridge, and one end of the first tube portion 30a. It has the 2nd pipe part 30b, and the 3rd pipe part 30c connected to the other end of the 1st pipe part 30a, and the denitrification tank 21. The first pipe portion 30a exchanges heat between the membrane permeate flowing in the membrane permeate outlet piping 30 and the high-temperature organic substance supplied to the methane fermentation tank 12 by the raw material supply means 14. This is an example of heat exchange means for heating the membrane permeate, and corresponds to a configuration in which a part of the membrane permeate outlet pipe 30 is passed through the solubilization tank 15.

  Further, a suction pump 32 is interposed in the second pipe portion 30b of the membrane permeate discharge pipe 30, and the membrane separation means 13 suctions and filters the digested sludge in the methane fermentation tank 12 by the suction pump 32. is there.

Hereinafter, the operation of the above configuration will be described.
The organic substance is charged into the solubilization tank 15 and solubilized in a liquid (or slurry) form in the solubilization tank 15, and then flows from the solubilization tank 15 through the raw material supply pipe 16 into the methane fermentation tank 12. The methane fermentation process is performed in the methane fermentation tank 12. Further, the digested sludge in the methane fermentation tank 12 is solid-liquid separated by the membrane separation means 13 and the solid content is concentrated. At this time, the membrane permeate that has permeated through the separation membrane 19 of the membrane separation means 13 is sucked by the suction pump 32, flows through the membrane permeate discharge pipe 30, and is biologically treated in the denitrification tank 21 and the nitrification tank 22. Then, it is discharged into a river as a treatment liquid.

  In addition, as an organic substance, there exist distillation waste liquid etc. which generate | occur | produce, for example, when making distilled spirits, such as shochu and whiskey, and such a distillation waste liquid is a solubilization tank in the state which usually has a temperature of about 70-80 degreeC. 15 is input. Moreover, the temperature of the digested sludge in the methane fermentation tank 12 is maintained within a range of about 35 to 60 ° C., and the temperature of the organic substance supplied to the methane fermentation tank 12 is higher than the temperature of the digested sludge in the methane fermentation tank 12. Is also hot. In addition, the methane fermentation tank 12 and the solubilization tank 15 are heated with a heat insulating material or heated with a heater or the like.

  When the high-temperature organic substance as described above is subjected to methane fermentation, the membrane permeate passes from the second pipe part 30b of the membrane permeate outlet pipe 30 through the first pipe part 30a to the third pipe part 30c. At this time, since the temperature of the organic substance in the solubilization tank 15 is higher than the temperature of the membrane permeate flowing in the first pipe part 30a, the inside of the first pipe part 30a is Heat exchange is performed between the flowing membrane permeate and the high-temperature organic substance in the solubilization tank 15 to heat the membrane permeate in the first pipe portion 30a.

  As a result, a decrease in the temperature of the membrane permeate in the membrane permeate outlet pipe 30 is suppressed, and accordingly, a decrease in the solubility product of MAP is suppressed (note that the solubility product of MAP decreases as the temperature decreases). , It becomes an environment in which inorganic crystals of MAP are difficult to precipitate, and it is possible to suppress the precipitation of MAP on the inner peripheral surface of the membrane permeate outlet pipe 30.

  Thereby, since the addition amount (use amount) of chemical | medical agents, such as salt iron, can be reduced significantly, it is possible to reduce cost, and also the inside of the methane fermentation tank 12 is easily optimal for methane fermentation. The pH can be maintained.

  Moreover, since the membrane permeate is heated using the temperature of the high-temperature organic substance supplied to the methane fermentation tank 12, the original temperature of the organic substance can be used effectively, and the cost can be further reduced. it can.

  In the first embodiment, as shown in FIG. 1, the raw material supply means 14 has a solubilization tank 15, but when the organic substance of the raw material has fluidity, It may replace with the solubilization tank 15 and may have the storage tank 33 which stores an organic substance. In this case as well, the first pipe portion 30 a of the membrane permeate discharge pipe 30 is provided at the bottom of the storage tank 33, and heat exchange is performed between the membrane permeate and the organic substance in the storage tank 33. May be performed. Or you may arrange | position the storage tank 33 in the front | former stage or back | latter stage of the solubilization tank 15. FIG.

Next, a second embodiment of the present invention will be described with reference to FIG.
The membrane permeate outlet pipe 30 is a second pipe portion 30a inserted into the raw material supply pipe 16, and a second permeate passage of the membrane cartridge and one end of the first pipe portion 30a. It has a pipe part 30b and a third pipe part 30c communicating with the other end of the first pipe part 30a and the denitrification tank 21. The heat exchanging means 34 is a double pipe in which a part of the membrane permeate outlet pipe 30 is passed through the raw material supply pipe 16 by the first pipe portion 30a on the inner pipe side and the raw material supply pipe 16 on the outer pipe side. It has a structure. The heat exchange means 34 exchanges heat between the membrane permeate flowing in the membrane permeate outlet piping 30 and the high-temperature organic substance supplied to the methane fermentation tank 12 by the raw material supply means 14 to allow the membrane permeation. The liquid is warmed.

Hereinafter, the operation of the above configuration will be described.
The membrane permeate flows from the second pipe part 30b of the membrane permeate outlet pipe 30 to the third pipe part 30c through the first pipe part 30a. At this time, the flow that flows in the raw material supply pipe 16 Since the temperature of the organic substance having the property is higher than the temperature of the membrane permeate flowing in the first pipe 30a, the temperature of the membrane permeate flowing in the first pipe 30a and the raw material supply pipe 16 is high. Heat exchange is performed with the organic substance, and the membrane permeate in the first tube portion 30a is heated.

  As a result, a decrease in the temperature of the membrane permeate in the membrane permeate outlet piping 30 is suppressed, and a decrease in the solubility product of MAP is suppressed, resulting in an environment in which inorganic crystals of MAP are difficult to precipitate. It is possible to suppress MAP from being deposited on the inner peripheral surface of 30.

  In the second embodiment, the methane fermentation tank 12 and the solubilization tank 15 communicate with each other via the raw material supply pipe 16, but the solubilization tank 15 is not provided and the solubilization process is unnecessary. You may apply to the methane fermentation processing apparatus which supplies a liquid (or slurry-like) organic substance to the methane fermentation tank 12 from the raw material supply piping 16. FIG.

  In the second embodiment, a part 30 a of the membrane permeate outlet pipe 30 is inserted into the raw material supply pipe 16, but a part of the raw material supply pipe 16 is inserted into the membrane permeate outlet pipe 30. May be.

Next, a third embodiment of the present invention will be described with reference to FIG.
The heat exchanging means 35 forms a part 16a of the raw material supply pipe 16 in a state where the outer peripheral surface of the part 30a of the membrane permeate discharge pipe 30 and the outer peripheral surface of the part 16a of the raw material supply pipe 16 are in contact with each other. The permeated liquid outlet pipe 30 has a configuration wound around the outer peripheral surface of a part 30a.

  According to this, heat exchange is performed between the membrane permeate flowing in the membrane permeate outlet piping 30 and the high-temperature organic substance in the raw material supply pipe 16, and the membrane permeate in the membrane permeate outlet piping 30. Is warmed.

  In the third embodiment, the part 16a of the raw material supply pipe 16 is wound around the outer peripheral surface of the part 30a of the membrane permeate outlet pipe 30, but the part 30a of the membrane permeate outlet pipe 30 is used as the raw material. You may wind around the outer peripheral surface of the part 16a of the supply piping 16. FIG.

Next, a fourth embodiment of the present invention will be described with reference to FIG.
The raw material supply means 14 includes a solubilization tank 15, a raw material supply pipe 16, a supply pump 17, and an external circulation pipe 37 that takes out a liquid organic substance stored in the solubilization tank 15 from the bottom and returns it to the top. And a circulation pump 38 provided in the external circulation pipe 37.

  The methane fermentation treatment apparatus 11 is provided with a heat exchanger 41 (an example of a heat exchange means), and the heat exchanger 41 is an organic substance in the external circulation pipe 37 via water (an example of a heat medium). Is exchanged with the membrane permeate in the membrane permeate outlet pipe 30.

  That is, the heat exchanger 41 includes therein water 41 a, a circulation passage 41 b through which the water 41 a circulates, and a pump 41 c through which the water 41 a is circulated. Heat exchange is performed by circulating through the circulation passage 41b while contacting between the outer periphery of the part and the outer periphery of a part of the membrane permeate outlet pipe 30.

Hereinafter, the operation of the above configuration will be described.
By driving the circulation pump 38, the organic substance solubilized in the liquid (or slurry) form in the solubilization tank 15 flows in the external circulation pipe 37 and the inside of the solubilization tank 15 is agitated. At this time, the temperature of the liquid organic substance flowing in the external circulation pipe 37 is higher than the temperature of the membrane permeate flowing in the membrane permeate outlet pipe 30, so the membrane permeate in the membrane permeate outlet pipe 30. And the high-temperature organic substance in the external circulation pipe 37 are subjected to heat exchange via the water 41a (heat medium) of the heat exchanger 41, and the membrane permeate in the membrane permeate lead-out pipe 30 is exchanged. It is warmed. Thereby, the temperature fall of the membrane permeate in the membrane permeate lead-out piping 30 is suppressed, and the decrease in the solubility product of MAP is suppressed.

In the fourth embodiment, water is used as an example of the heat medium of the heat exchanger 41, but is not limited to water, and liquids such as oil and ethylene glycol may be used.
In each of the above embodiments, heat exchange is performed between the organic substance and the membrane permeate, and the high-temperature organic substance having a reduced temperature is directly supplied into the methane fermenter 12. When the high-temperature organic substance adversely affects the temperature maintenance in the methane fermentation tank 12, the high-temperature organic substance is cooled to an appropriate temperature by heat radiation or the like before or after the heat exchange means, and then the methane fermentation tank 12 You may supply.

DESCRIPTION OF SYMBOLS 11 Methane fermentation processing apparatus 12 Methane fermentation tank 13 Membrane separation means 14 Raw material supply means 15 Solubilization tank 16 Raw material supply piping 19 Separation membrane 30 Membrane permeate outlet piping 30a First pipe part (heat exchange means)
33 Storage tanks 34, 35 Heat exchange means 41 Heat exchanger (heat exchange means)
41a Water (heat medium)

Claims (6)

A methane fermentation tank for performing methane fermentation of organic substances in the digested sludge, and a raw material supply means for supplying the methane fermentation tank with an organic substance having fluidity and higher temperature than the digested sludge in the methane fermentation tank. , Having membrane separation means,
A methane fermentation treatment apparatus for performing a methane fermentation treatment while concentrating solids in digested sludge in a methane fermentation tank by a membrane separation means,
A membrane permeate outlet pipe for taking out the membrane permeate permeated through the separation membrane of the membrane separator means, a membrane permeate flowing in the membrane permeate outlet pipe and an organic substance supplied to the methane fermentation tank by the raw material supply means; A methane fermentation treatment apparatus comprising heat exchange means for heating the membrane permeate by exchanging heat between the two. The raw material supply means has a solubilization tank for solubilizing organic substances in liquid or slurry form,
The methane fermentation treatment apparatus according to claim 1, wherein the heat exchange means has a configuration in which the membrane permeate outlet piping passes through the solubilization tank. The raw material supply means has a storage tank for storing an organic substance having fluidity,
The methane fermentation treatment apparatus according to claim 1, wherein the heat exchange means has a configuration in which the membrane permeate outlet piping passes through the storage tank. The raw material supply means has a raw material supply pipe for supplying a fluid organic substance to the methane fermentation tank,
The methane fermentation treatment apparatus according to claim 1, wherein the heat exchange means has a configuration in which the membrane permeate discharge pipe and the raw material supply pipe come into contact with each other. The methane fermentation treatment according to claim 1, wherein the heat exchange means exchanges heat between the membrane permeate and the organic material supplied to the methane fermentation tank by the raw material supply means via a heat medium. apparatus. Supply organic substances that are solubilized in liquid form at a higher temperature than the digested sludge in the methane fermenter to the methane fermenter, and perform the methane fermentation process while concentrating the digested sludge in the methane fermenter by membrane separation means A methane fermentation treatment method,
The membrane permeate is heated by exchanging heat between the membrane permeate flowing through the separation membrane of the membrane separation means and flowing in the membrane permeate outlet pipe and the organic substance supplied to the methane fermentation tank. A characteristic methane fermentation treatment method.

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